Dead Man Walking is about how you shouldn't kill people.

That seems fairly straightforward, right? "Thou shalt not kill" is one of the Ten Commandments; every state, and every country, and every moral or political philosopher, agrees that murder is wrong. "Don't kill" seems like a universal baseline for morality.

So everyone agrees. Close the book, go home, be happy, and commit sins lesser than murder, like eating double-stuff Oreos or watching Seinfeld. All is well. Right?

Well, not exactly right. Because if you start thinking about it, the whole not-killing-people thing starts to get a little tricky. Yes, don't kill—but what about during wars? And what if someone does commit murder? What should the punishment be? If we all agree that murder is super-wrong, then it seems like murder requires a super-punishment—like, maybe, death? If killing is wrong, does that mean it's right to kill killers? Or does that mean that any killing, even if it's done by the state, is wrong?

Dead Man Walking thinks that the answer to that last question is "yes": any and all killing is wrong. "Kings and Popes and military generals and heads of state have killed, claiming God's authority and God's blessing. I do not believe in such a God," Sister Prejean writes (1.116).

Well, then, what do you do about people who murder? Sister Prejean's on that: "In an ideal world, there would be no need for retribution. But in real societies, punishing the guilty is as integral to the function of law as exonerating the innocent and preventing crime" (7.6). In other words, there needs to be some kind of punishment for murder, but the issue of killing a killer presents a contradiction that both death-penalty supporters and opponents have to wrestle with.

Prejean's personal efforts to wrestle with these issues have resonated with a lot of people. Her book became a bestseller when it was published in 1993, and it inspired a high-profile 1995 film starring Susan Sarandon as Prejean and Sean Penn as a Death Row inmate. The book was also adapted into an opera in 2000 and a play in 2002; the play was written by actor Tim Robbins, who also wrote the screenplay for the movie.

Sister Helen Prejean continues to work for death penalty abolition. In 2004, she wrote a book called The Death of Innocents about two men she believes were wrongly executed. As she says in the twentieth-anniversary edition of her book, "The fire in my soul still burns bright, and I know, with God's good grace, until my dying breath, that I'm going to work to put government killing machines in museums behind blue velvet ropes where they belong."

Preach, sister.

Twenty years ago, when Dead Man Walking was first published, people cared about it because the death penalty was a controversial issue. Some people supported capital punishment, and it was legal in some states. Some people didn't support it, and it was illegal in some states. Those for and against tried to convince each other. Sometimes a legal death penalty state would switch to banning the practice, and sometimes the opposite would happen. Folks argued about it; politicians argued about it; everyone argued about it; so everybody cared.

But now we all agree on death penalty policy, so the book is no longer relevant.

…Yeah, no. This issue is every bit contentious as it always ways—maybe even more contentious now that several states have been botching executions. Two decades after Prejean published her book, America is still torn, conflicted, indecisive, and argumentative about the death penalty. There has been some movement away from it in some states. For example, in 2011, Illinois banned the death penalty after an 11-year moratorium, originally imposed because of fears that the death penalty system was so flawed that innocent people were being executed.

But at the same time, the Supreme Court still maintains that the death penalty is constitutional, meaning that it does not violate the prohibition on "cruel and unusual punishment" in the Eighth Amendment. Thirty-two states continue to use the death penalty, including Louisiana, where Prejean's book is set.

News flash: if you live in a death-penalty state, your tax dollars go to kill people. If you don't live in a death-penalty state, then life imprisonment is the most extreme punishment possible for murder. Prejean's idea, though, is that no matter where you live, the death penalty is a basic issue of human rights. If killing is happening anywhere, she believes, then it deserves attention. After all, you never know when you yourself might be a target—innocent or not.